It's not as glamorous as it looks, says Britain's Got Talent runner-up and worldwide sensation Susan Boyle in her first tell-all interview after her whirlwind stint on the British talent show that for a while landed her in a London clinic due to fatigue and exhaustion.

"The impact, like a demolition ball. You know, and anyone who has that kind of impact - finds it really hard to get a head around it," Boyle told Meredith Vieira of the Today show, where snippets of the interview will be broadcast. The whole thing will be aired on Britain's Got Talent's stateside cousin America's Got Talent, also on NBC.

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"I've got to be honest here. I guess I had to get my head around it, but through the - the guidance of a great team, and they are very good, I was able to see that in perspective and really turn that around a little."

Boyle will largely talk about her journey from "obscurity" to the "long journey" that she took on Britain's Got Talent and the subsequent tour.

Meanwhile, Simon Cowell, American Idol judge, creator of both Britain's Got Talent and America's Got Talent, and director of her upcoming album, says that Boyle's debut will no doubt "surprise a lot of people."

"We're not going to throw out some souvenir album of show tunes," Cowell told Extra, adding that Boyle's breakthrough and as yet most memorable rendition of I Dreamed a Dream is not a clear indication of how her album will sound like, so fans should think twice before second-guessing its content.

"She's going to surprise a lot of people with this record," Cowell promised.

Boyle is set to appear in an interview on Wednesday's Today show and as part of a special edition of America's Got Talent airing that same evening on 9pm.